So called "stop leak" compositions have long been used for stopping leaks in automobile cooling systems. Many of these compositions are aqueous suspensions of a particulate material that is entrained in the leak, thereby plugging it. Particulate materials that were used include linseed meal and metal flakes. However, these compositions are often not effective in completely stopping the leak, particularly under pressure, resulting in excessive loss of the coolant.
For many years stop leak compositions were improved by the addition of an asbestos fiber to the particulate material. However, the use of asbestos was not always effective and there are now known to be health and environmental problems associated with the use of asbestos.
It is also known to use asbestos fiber in an antifreeze composition to provide some leak stopping ability to the antifreeze. These antifreezes can be made by dispersing the asbstos fiber directly into ethylene glycol.
In the above-cited Ser. No. 361,546 is disclosed a stop leak composition that is substantially more effective than the above-discussed prior art stop leak compositions in the stopping of leaks. Therein is disclosed a composition for the stopping of leaks in a leaky container, preferably a heat exchange system such as automobile cooling systems. Which comprises a suspension in a liquid medium of a particulate material of a size and in an amount sufficient to become entrained in the leak, and fibrillated fiber coacting with the particulate material to seal the leak by an entwining action.
In copending application Ser. No. 578,857 "Leak Stopping Composition and Method", filed concurrently herewith by A. G. Barber, is disclosed a composition for the stopping of leaks in a coolant system which comprises a suspension in a liquid medium, preferably an antifreeze composition, of a fibrillated fiber in an amount which is effective for the stopping of leaks.
Typically stop leak compositions are supplied to the consumer in the form of a concentrate that is added to the fluid of the coolant system. In the case of a preferred stop leak of Ser. No. 361,546 above, a concentrate is formed comprising an aqueous suspension of a particulate material and a fibrillated fiber. This concentrate is then added by the consumer to the fluid of the cooling system, which is typically an antifreeze composition. The concentrate is then diluted by and dispersed throughout the cooling system to provide an effective amount of particulate material and fibrillated fiber to plug leaks in the cooling system.
An alternative method of supplying a stop leak to the consumer is to provide an antifreeze composition, which is almost entirely an alcohol containing small amounts of corrosion inhibitors and other additives, and also containing a stop leak material. Thus, as the consumer periodically adds to or replaces the antifreeze in his automobile cooling system, a stop leak composition is added automatically.
Providing an antifreeze to the consumer containing a stop leak, such as a stop leak of above-cited, Ser. No. 361,546 requires the addition of extra process steps and ingredients that add to the expense of manufacture but do not increase its effectiveness in most of the systems in which it used, since most cooling systems in which antifreeze is used, are leak-free. However, there are consumers, who, as a precautionary measure, wish to add a stop leak composition to their cooling system as they add antifreeze, even though their cooling system is free of leaks. In order to meet the need of these consumers, it would, therefore, be desirable to provide an antifreeze composition with a leak stopping ability in addition to providing the normal antifreeze not having leak stopping ability. However, considering the problems described above, such an antifreeze composition would have to be economical to manufacture and have a minimum amount of additional addivites. Also the manufacture of such a "stop leak" antifreeze should be easily accomplished by a minimal alteration of existing manufacturing practices for making antifreeze. It would then be easy to quickly modify the manufacturing process to make either a stop leak containing or a stopleak free antifreeze.
In order to prepare a suspension of fibers in a liquid medium to make a stop leak, the fiber is dispersed in the medium using a mixer or the like. When a nonfibrillated fiber is used, such as asbestos, the fiber can be effectively dispersed by merely mixing the fiber directly into aqueous or alcoholic media. However, it was found that attempts to disperse fibrillated fibers, such as fibrillated polyamide fibers, were only partially successful, since many of the fibers adhered together in clumps and were not dispersed. In a medium that is a predominately water, this problem can be solved, as is disclosed in the above-cited Ser. Nos. 361,546 and 578,857, by using dispersants, such as various surfactants, and clay suspending agents.
These dispersants are satisfactory when the liquid medium is mostly water. However, when the fibrillated fibers are dispersed directly in alcoholic media, the problem of incomplete dispersion of the fibers also exists, the fibrillateed fibers being only partially dispersed with many of the fibers remaining in undispersed clumps. The dispersants used in aqueous media to solve the clumping problem are not effective in eliminating the clumping problem in alcoholic media.
Therefore, in the manufacture of alcoholic-based stop leak antifreezes containing a minimum of added water, and wherein a fibrillated fiber is dispersed therein, there has been a continuing difficulty in dispersing fibrillated fibers. Therefore, it would be desirable to have a method to effectively disperse fibrillated fibers in alcoholic media with a minimum of added water, to form stop leak antifreezes. Accordingly, an object of the invention is to provide a method for the dispersion of fibrillated fibers in alcholic media with a minimal addition of water.